The software reliability of component-based development depends on component reliability,but component reliability is affected by test coverage and usage frequency.Therefore,the reliability evaluation of new components is often low.When a newly developed component is introduced into mature software,no matter the importance of component,the software reliability evaluation value will change greatly.To solve this problem,taking a software as the research object, a Markov chain software model based on functional scenario is established. the importance of each component in the model is evaluated by analytic hierarchy process.On this basis,a software reliability evaluation model based on component importance is established.The simulation results show that the model can more accurately reflect the software reliability level of component-based development.